A platform for community discussion. Free, open and simple.

If you don't want to be required to make a @Facebook account, and don't want to require your group to to do the same, then, you can create a community discussion platform using @discourse:
@discourse provides a fully functional environment for socializing online allowing you to easily customize all the features you're asking for.
@discourse development te…See more

Arun Sathiya- Prev, marketing at Freshworks Inc.

I have to stress that Discourse is the best forums experience ever. A bit pricey hosting, but the snappy UX compliments it.